A helicopter hovers over its landing pad on BP's massive Thunder Horse platform in the Gulf of Mexico. The $5 billion project, 10 years in the making, is designed to pump 250,000 barrels a day from a field in 6,000 feet of water.

Photo: BRETT COOMER, CHRONICLE

A helicopter hovers over its landing pad on BP's massive Thunder...

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Thunder Horse lists after an encounter with Hurricane Dennis in July 2005.

Befitting its name, BP's massive Thunder Horse offshore platform has been beset by dark clouds ever since it was on the drawing board.

After fiascos involving its stability and even its very name, BP finally has its eye on the silver lining — a huge deposit of oil and natural gas under the Gulf of Mexico that will boost the company's bottom line as well as the nation's declining production.

"When it's fully up to speed, it's 250,000 barrels a day. That's significant production at a time when we're trying to get as much energy security as we can," Bob Malone, chairman and president of BP America, said after his first visit to Thunder Horse last week.

It's been a long time coming, a decade since BP discovered the oil field with up to 1.5 billion barrels beneath 6,000 feet of water.

To reap that bounty, the company set out to build the biggest, boldest floating oil and gas production facility in the world, at a development cost of $5 billion.

With capacity to produce 250,000 barrels of oil and 200 million cubic feet of natural gas per day, Thunder Horse could energize 6.5 million homes.

BP and its contractors had to invent equipment, because much of what was available couldn't accommodate the project's size and scope as well as massive pressures and temperatures in the deep water.

Problems delayed the scheduled startup date from 2005 to late next year.

Ballast system failures left the mighty platform listing 20 degrees after Hurricane Dennis blew through the Gulf in July 2005.

Nearly a year later a critical piece of equipment on the seabed sprung a leak, forcing BP to haul it and three others onshore for repairs.

And long before it shipped out to sea, the original name for the platform — Crazy Horse, for the rock band — drew the ire of descendants of the Lakota Sioux warrior and spiritual leader. Their tradition holds
it sacrilegious to use the name in a nonspiritual context.

Malone traveled to a South Dakota reservation, apologized, and BP changed the name to Thunder Horse in 2002.

One of many difficulties

Thunder Horse's troubles came amid unrelated events that damaged BP's performance and marred its image: the March 2005 explosion at its Texas City refinery that killed 15 people; an investigation into improper propane trading; and last year's oil spill from a corroded pipeline system BP operates in Alaska's Prudhoe Bay, the largest U.S. oil field.

BP CEO Tony Hayward has promised improvement. The company is streamlining management and upgrading U.S. refineries. Earlier this month the company struck deals with the Justice Department to settle criminal investigations into the blast, trading and oil spill.

And BP is methodically making sure everything works properly on Thunder Horse.

"The big problems we faced are sort of manifestations of stretching that envelope," said Dan Replogle, performance unit leader for Thunder Horse. "We had to develop the technology in order to do this. We had a lot of confidence in it, but there were things we learned, and a few things we learned the hard way."

Big Atlantis project

Last year BP's production fell 5 percent to 3.8 million barrels a day and is expected to be flat this year.

However, analysts have largely forgiven the lapses in anticipation of Thunder Horse and with the startup last month of another major BP Gulf platform, Atlantis.

Both platforms are part of BP's $15 billion commitment to Gulf operations including its Holstein, Mad Dog and Na Kika platforms, the Mardi Gras deep-water pipeline and interests in projects run by other companies.

When it hits full tilt, Thunder Horse alone will boost overall U.S. production by 3.6 percent. Add Atlantis at full capacity, and the boost will be 6.4 percent.

"Adding 6.4 percent is probably the biggest surge of production from just two locations that we've experienced in a decade in this country," said John Parry, an analyst with John S. Herold.

U.S. production fell from 8.3 million barrels a day to 6.9 million barrels from 1996 through last year, Parry said. Thunder Horse and Atlantis will restore about a third of the loss.

Exxon Mobil Corp. has a 25 percent interest in Thunder Horse.

Nearly 1,000 feet wide

Thunder Horse, a 59,500-ton structure about 150 miles southeast of New Orleans, is almost 1,000 feet wide.

Pipes known as risers that will bring oil to the platform from the seabed are so heavy that they're encased in buoyant insulation to keep them from pulling down the structure.

Five decks stretch 15 stories above the water's surface. Jet engines that typically would be found on an airliner drive five turbines to power the facility — enough electricity for 80,000 homes onshore.

The drilling system can do two jobs at once, saving time and money, and can drill up to 30,000 feet through rock, sediment and salt below the seabed to the reservoir.

Forty-six ballast tanks keep the semisubmersible floater level.

And its living quarters can house up to 289 people.

"My reaction was, 'Holy mackerel, look at the size of that thing,' " Malone said of his first view of Thunder Horse.

Every system is monitored from a control room, where computer screens display charts, maps and radar images.

Screens also display images from cameras on truck-size submarines that can cut, grab and turn equipment on the seabed.

Hoisted above the "moon pool," the open area in the middle of the platform where the drill descends into the ocean, is a massive piece of equipment covered with intricate tools that can descend to the ocean floor and prevent a blowout if the flow of hydrocarbons or drilling fluid becomes unstable.

Thunder Horse shipped out from Corpus Christi to its current home in April 2005.

But the installation's vulnerability to technological glitches became glaringly clear after Hurricane Dennis hit three months later. The platform, which had been evacuated, flooded and listed.

Replogle said months of study revealed that defects in the hydraulic control system let ballast water shift from full to empty tanks.

By the time Hurricane Katrina struck that August, Thunder Horse had been stabilized.

The repairs cost $250 million, and BP aimed to start pumping in August 2006.

Another setback

But in May of that year, pressure testing revealed a leak in a manifold, a piece of equipment that controls the flow of oil and natural gas from multiple wells to the platform.

Again, production was delayed as BP investigated the problem, which turned out to be a crack through a pipe weld.

The company spent months sealing off wells and bringing the equipment to shore for repairs, with costs in the hundreds of millions of dollars.

"You have a 300-person hotel. You have a dual capability drilling system. You have basically a Prudhoe Bay flow station sitting on a platform. It's very complex, but that also makes it very dynamic and challenging," said Tommy Hassold, who as offshore installation manager is essentially the captain of the ship.

Drilling has continued during the production delays, and crews repeatedly test the onboard equipment, circulating oil and natural gas through the facility.

"We either mothball this equipment while we wait for them or we use it so we can identify any problems," said Steve Robichaux, topsides operations team leader, during a recent tour.

"So, our equipment is actually working."

Crews are ready for oil to flow. Pam Baker, a former Navy aircraft mechanic who now takes care of the jet engines that provide power aboard the platform, said it's been a long-awaited challenge.